The present invention generally relates to seat belt retractors and more particularly to a seat belt retraction mechanism capable of reducing the rewind force that acts on the shoulder of an occupant via the shoulder belt portion of the seat belt.
Accordingly the invention comprises: a seat belt retractor adapted to be secured about a seated occupant comprising: a spool having a length of seat belt wound thereon for securement of the occupant, a portion of the seat belt forming a shoulder belt portion, the spool rotationally supported upon a frame; a tension reducing first means for controlling the amount of spring force transmitted from a rewind spring to the spool and hence the force applied to the shoulder of the occupant via the shoulder belt portion of the seat belt, the first means comprising: a cylindrical first spool, aligned to an a rotationally axis of the spool, having an ungrooved, smooth body operatively connected to the spool to rotate with the spool; a second reel positioned remote from the first reel including a tapered peripheral surface having a continuous spiral groove of varying diameter thereon, the second reel having an axis of rotation parallel to that of the first reel; a rewind spring operatively connected to the second reel for providing a rewind force to rewind the seat belt upon the spool; a flexible link joining the first and second reel and for transmitting the force of the spring to the first reel, the link wound about the second reel within the spiral groove and wound about the first reel. The link preferably extends away from the second reel, in a direction generally perpendicular to the axis of rotation of the second reel independent of the position of the link within the groove. This orientation avoids excess wear to the lip of the groove or groove segment and reduces associated acoustic noise.
One advantage of the present invention is that as the flexible link, cable or cord is moved between an upper and a lower reel it will extend from the lower or first reel toward the upper or second reel in a general vertical manner. This is not true of the prior art as shown in U.S. Pat. No. 5,628,470 or in U.S. Pat. No. 5,409,176, in which grooves are located on an upper reel. As the cable in these prior art retractors is repositioned between the upper and lower reels the cable will typically be inclined at an angle to the axis of both reels and grooves. This relationship causes the cable to rub upon the outer edges of the groove causing an audible noise and causing the wearing of the typically plastic reels. This is not the case in the present invention.
It is an object of the present invention to provide a seat belt retractor with an improved tension reduction or comfort mechanism.
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.